Various controls for rolling mill roll gaps are known and the problem presented has been that that means for detecting changes in the roll gap have been indirect; that is, they have measured relative movement of parts of the mill or the rolls other than the actual surfaces of the rolls on a center line extending between the axes of rotation of the rolls themselves. Another difficulty has been that the signal for the control equipment was initiated at a location remote from the actual roll pass and there was lost motion and/or change in the amount of displacement at the signal detection location as compared with the roll gap.
While it is not possible to monitor a roll gap while material is actually passing through the gap; this invention obtains the same effect by means of sensors, such as contacts which touch the rolls, just to one side of the material which is being rolled. The preferred embodiment uses contacts, but proximity sensors or other types can be used, if desired.
This invention provides several ways which overcome the problem that the roll gap is so small that it does not provide clearance for stiff contacts to extend between the rolls. Unless the contacts and their connectors are rigid, accurate signal response to roll gap changes cannot be obtained.
This invention provides such clearance by offsetting axially the contacts, or other sensors, that detect change in roll spacing, and by providing grooves in a confronting face of one roll to obtain the necessary clearance from the circumference of the other roll for receiving a rigid detection device.
In a modified construction of the invention, collars at the ends of the rolls, near the roll necks, are provided and made integral with the roll structure so as to provide, in effect, extensions of the circumferential surfaces of the rolls themselves.
The contacts that bear against the roll surfaces are connected to rigid arms that operate a transducer located close to the rolls themselves. This avoids lost motion in the motion-transmitting parts between the contacts and the transducer; and also makes the apparatus compact and inexpensive.
Other objects, features and advantages of the invention will appear or be pointed out as the description proceeds.